The object of the invention is motor vehicle bodyshell structures and more particularly the points of anchoring of the rear shock absorbers of the vehicle on these bodyshells.
With the development of electric or hybrid vehicles, vehicle architectures are being increasingly frequently encountered in which the rear floor of the vehicle is raised, meaning that it disposed more at the top level of the wheel well instead of being disposed at an intermediate height between the base of the bodyshell and the top of the wheel wells.
As an example, these raised floors make it possible to free up space to install electric storage batteries. But the requirements of impact resistance of the vehicle, especially resistance to certain types of rear-end impact, applied at a standardized height relative to the vehicle, are more favorable to low positioning of the frame rails of the longitudinal structural reinforcements of the vehicle.
To be able to free up the space necessary for positioning of the batteries and at the same time to satisfy the requirements of rear-end impact, certain vehicle architectures therefore have frame rails that are locally offset upwards at the rear of the vehicle. Because of this offset, the rear frame rail, assuming equal section, is more subject to deformation during an impact than an equivalent straight frame rail.
In addition, the rear end of the frame rail in these architectures is no longer positioned facing the normalized point of impact during rear-end impact tests.
This therefore necessitates increasing the section and therefore the mass of the frame rails, as well as adding complementary structure portions designed to transfer the impact energy from the height at which it is applied to the front of the frame rail.
Another problem resulting from the elevation of the rear floor of the vehicle is that the shock absorber fixation towers, which traditionally are attached to the frame rails, tend to be disposed below the vehicle floor and are no longer connected in optimum manner to the upper part of the bodyshell. Thus they cannot be fixed in synergy with this upper part of the bodyshell in order to dissipate part of the forces transmitted by the shock absorber.